KR20160018658A - Rotary encoder - Google Patents

Abstract

The present invention relates to an inductive displacement sensor and its associated method for sensing the relative displacement between two relatively moving parts of a power tool. The displacement sensor includes a stator element having a first conductive pattern and a rotor element having a second conductive pattern, both of which are relatively movable. The first conductive pattern and the second conductive pattern are mutually inductively coupled. The first conductive pattern is configured to receive a high frequency excitation signal having a substantially constant amplitude. The high frequency excitation signal causes an intermediate signal to be generated in the second conductive pattern by mutual induction between the first conductive pattern and the second conductive pattern. The intermediate signal represents the relative displacement between the stator element and the rotor element.

Description

Rotary encoder {ROTARY ENCODER}

The present invention relates to a power tool having a sensor for sensing displacement and a method for sensing displacement in a power tool.

The invention relates particularly to the use of an inductive rotary encoder with an inductive-type rotary encoder for sensing the displacement between two relatively moving parts of the power tool and between the two relatively moving parts of the power tool using an inductive rotary encoder The method comprising:

A power tool, such as a screwdriver, nut runner, or drill, typically has at least one detector device of some form for sensing one or more parameters, such as the relative angular displacement between two relatively moving portions of the power tool . One or more parameters may be used, for example, for monitoring purposes or feedback control.

The detector device typically relies on applications that are configured to measure linear displacements or rotational displacements, i.e., angular displacements.

In addition, the detector device is typically characterized by a contact detector device or a non-coherent detector device, depending on whether or not the physical contact is required by the detector device with respect to the object on which the wiring is relatively moving.

Various detector devices are used today across a variety of different systems to sense the displacement, or relative position, between two relatively moving elements, such as between a rotatable element and a stop element. These detector devices are typically referred to as syncroxes, resolvers, encoders, slip rings or transducers, and may be used in conjunction with physical sensing principles such as optical, magnetic, inductive, capacitive, or eddy current physical sensing principles .

An optical detector device typically implements a disk mounted on a rotatable object, such as a rotating shaft, wherein the disk is made of glass or plastic with a transparent area and an opaque area. These regions are exposed to light from a light source. The resulting light, i. E. The optical pattern, is received by the photo detector array reading the optical pattern. The read optical pattern is then processed to provide the position of the disk, i.e., the angle of the shaft.

Magnetic detection devices typically perform a series of stimuli of the same distance provided in alternating Arctic-Antarctic configurations. A series of stimuli are mounted on a rotatable object such as a rotating shaft. A magnetic sensor (typically a magnetoresistive or Hall effect) reads the magnetic pole position.

These positions can then be processed by a processing device similar to the optical detector device described above to determine the angle of the shaft.

The inductive detector device typically implements an inductive element in the form of at least one first coil mounted on a rotatable object of measurement, such as a rotating shaft, wherein the at least one first coil, during rotation of the object to be measured, And moves relative to at least one second coil. By applying energy to at least one second coil, current is induced in the first coil, because of mutual inductance, using alternating current (AC). The degree of electrical connection between the at least one first coil and the at least one second coil indicates a relative displacement between the at least one first coil and the at least one second coil.

The capacitive detector device typically uses a rotatable measurement target disk. When the object to be measured rotates, the disk changes the capacitance between the two electrodes of the capacitive detector device, the capacitance can be measured, and can be processed to provide an indication of angular displacement.

Eddy current detector devices typically use a high and low permeable, non-magnetic material-coded scale, which is detected and decoded by monitoring changes in the inductance of the AC circuit including the inductive coil sensor.

However, prior art detector devices tend to have one or more of the following disadvantages: they require large space, require complex circuit (s), cause high power consumption, are difficult to maintain, May be heavier, susceptible to external magnetic fields, provide less accuracy, or be less susceptible to wear.

These drawbacks adversely affect performance and / or cost for power tools, and these drawbacks make them unsuitable for use in power tools.

Accordingly, there is a need to provide improvements in the detector arrangement for sensing the relative displacement between the relatively moving parts of the power tool.

One object of the present invention is to provide a robust relative displacement sensor for a power tool.

A further object is to provide an accurate relative displacement sensor for a power tool.

A further object is to provide a relatively small relative displacement sensor that does not require much space when mounted inside a power tool.

A further object is to provide a relative displacement sensor that is less complex and less costly than known techniques in the prior art.

One or more of these objects is achieved by a displacement sensor for a power tool according to the invention as defined in claim 1. The displacement sensor includes a stator element and a rotor element configured for relative movement along the measurement path. The stator element comprises a first conductive pattern and the rotor element comprises a second conductive pattern. The first conductive pattern and the second conductive pattern are mutually inductively coupled. The first conductive pattern is configured to receive an excitation signal. The second conductive pattern is caused by mutual induction between the first conductive pattern and the second conductive pattern and is configured to produce an intermediate signal within the second conductive pattern. The resulting intermediate signal represents the relative displacement between the stator element and the rotor element. The excitation signal is a high frequency excitation signal with a substantially constant amplitude.

The fact that the excitation signal has a substantially constant amplitude can be defined as the amplitude having no information, i.e. amplitude modulation is not performed.

With respect to frequency, a displacement sensor for a power tool is achieved, which is robust with respect to electromagnetic interference, so that the excitation signal is far from the frequency generally associated with the source of electromagnetic interference present around the power tool. The phase of the intermediate signal will exhibit a relative displacement, i. E. Relative angular displacement between the rotor element and the stator element, or more precisely, the phase difference between the intermediate signal and the high frequency excitation signal will indicate a relative position.

Moreover, confinement for poor lateral alignment between the rotor element and the stator element is increased. In addition, the distance between the stator element and the rotor element can be increased with the maintained accuracy of the displacement sensor.

In addition, using the high frequency excitation signal, the conductive pattern of the stator element and the rotor element can each be implemented with a relatively small amount of inductance contained between them, and still provide sufficient impedance suitable for the configuration of the displacement sensor. In addition, it can constitute a conductive pattern of each, so that it can form a conductive element, that is, a coil, and each surrounding a region where there is relatively no conductive material / element, Lt; / RTI >

Moreover, the displacement sensor can be implemented with a small circuit configuration, since only one signal is needed, which is the form of the intermediate signal, when converting the sensor signal to a value representing the relative displacement between the rotor element and the stator element. This allows the production of displacement sensors with low form factor, light weight and low production costs. On the other hand, displacement sensors according to the prior art typically use different receive signals, each of which requires decoding performed by a dedicated decoding circuit to output a value indicative of the relative displacement.

The displacement sensor is an optional feature in that the high frequency signal is a signal having a frequency selected from a frequency range of 100 KHz to 100 MHz.

The displacement sensor is an optional feature in that the high frequency signal is a signal having a frequency selected in the frequency range of 1 MHz - 10 MHz.

The displacement sensor is an option, wherein the excitation signal is a multi-phase excitation signal comprising a plurality of high frequency excitation signals, each excitation signal being configured to have a plurality of phases.

Thereby, a displacement sensor for a power tool is achieved, wherein the displacement sensor has improved robustness with respect to resistance to failure, and the receiving circuit of the displacement sensor can be made of less complex circuitry. More specifically, using the multi-phase excitation signal, the circuit on the receiving side of the displacement sensor can be made less complex. Apart from implementing a less complex circuit on the receiver side of the displacement sensor, the displacement sensor is made more robust using a multi-phase excitation signal because only one receiver / decoder circuit is required on the receiver side. This is different from prior art displacement sensors, which typically require two separate receiver / decoder circuits on the receiver side. The use of only one receiver / decoder circuit on the receiver side makes the displacement sensor more robust against faults compared to using two receiver / decoder circuits. This disturbance affecting the receiver side of the displacement sensor can seriously affect the displacement sensor, especially the displacement sensor with two receiver / decoder circuits, because the signal strength at the receiver side is typically very weak, Lt; RTI ID = 0.0 > receiver / decoder < / RTI > circuitry. In contrast, the displacement sensor according to the present invention can operate correctly in an unscreened fashion, close to a power cable, such as a power cable connected to a motor of a power tool with a current of at least 60 amperes (A).

The displacement sensor is an optional feature and is characterized in that the multi-phase excitation signal is a 4-phase excitation signal with four phases including 0 degree phase, 90 degree phase, 180 degree phase and 270 degree phase.

This achieves a displacement sensor for a power tool in which the multi-phase excitation signal can be generated in an efficient manner because the 0 DEG phase and the 90 DEG phase are simply inverted to produce a 180 DEG phase of the multi- Phase can be generated. This configuration of the multi-phase excitation signal enables phase matching with respect to the configuration of the first conductive pattern of the stator element and the second conductive pattern of the rotor element. For example, if the second conductive pattern is configured to form alternating two-phase patterns that include a 0 DEG phase and a 180 DEG phase, i.e., in alternating and anti-phase patterns, the phase of the multi- 0 DEG and 180 DEG are supplied in a first conductive pattern such that a portion of the first conductive pattern supplied in the 0 DEG phase of the multi-phase excitation signal faces a portion of the second conductive pattern configured to form a 0 DEG phase, The first conductive pattern faces a portion of the second conductive pattern configured to form a 180 [deg.] Phase with a portion of the 180 [deg.] Phase.

The displacement sensor is an optional feature, wherein the multi-phase excitation signal is a three-phase excitation signal with three phases including a 0 degree phase, a 120 degree phase, and a 240 degree phase.

Thereby, a displacement sensor for a power tool is achieved, which uses a three-phase multi-phase excitation signal to enable relative displacement sensing of relatively moving parts associated with a three-phase motor.

The displacement sensor is an optional feature wherein the first conductive pattern of the stator element includes a series of drive coils extending along the measurement path of the stator element. A series of drive coils are arranged in a periodic repeating phase pattern. The phase pattern repeats n times along the measurement path. And the phase of the multi-phase signal is supplied to each drive coil of the phase pattern which is periodically repeated.

The displacement sensor is one option that is configured such that the phase of the gradually increasing multi-phase excitation signal in the sequence of the drive coils of the periodically repeated phase pattern is provided to each drive coil of the periodically repeated phase pattern .

The displacement sensor is an optional feature wherein the second conductive pattern of the rotor element includes a series of balanced receiving coils connected in series and extending along the measuring path of the rotor element, And facing the measurement path.

The displacement sensor is an option, with each receive coil of a series of receive coils formed with a periodically repeating balanced two-phase pattern repeated i-1 times along the measurement path so that each of the series of receive coils The adjacent loops of the receiving coil of the antenna are anti-phase.

Thereby, a displacement sensor for a power tool is achieved, in which a fault generated from an external magnetic field is effectively prevented from appearing in an intermediate signal.

The displacement sensor is an optional feature, further comprising a drive coil having a balanced rotor element. A balanced drive coil is coupled to the second conductive pattern and is configured to transfer the intermediate signal to the balanced receive coil of the stator element by a mutual induction formed between the balanced drive coil and the balanced receive coil.

Thereby, a displacement sensor for a power tool is achieved, in which the effect of the disturbance is reduced because the drive coils are balanced and the receive coils are balanced. The displacement sensor is an option, with each balanced drive coil and balanced receive coil each comprising two coil sections. The two coil sections are configured such that the current flow in the two coil sections flows in opposite directions to each other along the measurement path of the rotor element and the stator element.

Thereby, when the intermediate signal is transmitted from the rotor element to the stator element, a displacement sensor for the power tool is obtained in which the failure generated from the external magnetic field is effectively removed from the intermediate signal.

The displacement sensor is an optional feature that includes a signal generation circuit. The signal generating circuit is coupled to the first conductive pattern of the stator element. The signal generator is configured to generate an excitation signal and provide an excitation signal in a first conductive pattern to energize the first conductive pattern.

The displacement sensor is an optional feature, further comprising a single-phase signal processor circuit. The signal processor circuit is configured to receive and process a single phase received signal corresponding to an intermediate signal received at the stator element to provide an output signal indicative of a relative displacement between the rotor element and the stator element.

The displacement sensor is an optional feature that the single phase signal processor circuit includes a phase detection circuit configured to process the received signal to detect the phase difference between the received signal and the excitation signal to provide the output signal .

Due to the fact that the amplitude remains substantially constant, i. E. The fact that amplitude modulation is not performed, there may be no demodulation step at the receiving end. Further, since the excitation signal is a high frequency, it is desirable to perform at a high frequency so that a small part can be used, so that frequency adjustment is unnecessary for detecting the phase.

Thereby, a displacement sensor for a power tool is obtained in which the displacement sensor is resistant to such a failure, since the amplitude-modulated disturbance does not affect the phase difference.

The displacement sensor is an optional feature and the phase detection circuit is an I / Q demodulation circuit configured to output two quadrature signals representing the phase difference between the received signal and the excitation signal.

This achieves a displacement sensor for an electric power tool with improved displacement sensing, since the IQ-demodulator can detect the phase difference between the reference signal and the received signal, for example, in a simple and robust manner. Apart from the ease of detection and robustness, the use of an IQ-demodulator also provides cost efficiency in connection with the manufacture of displacement sensors, since the IQ-demodulator can be manufactured at relatively low cost.

The displacement sensor is an optional feature wherein the rotor element is configured to be attached to the first moving portion of the power tool and the stator element is configured to be attached to the second stationary portion of the power tool.

Thereby, a displacement sensor for a power tool capable of sensing the relative displacement between the first moving part and the second stationary part of the power tool is achieved.

The displacement sensor is an optional feature, wherein the rotor element and the stator element are formed as annular discs.

The displacement sensor is an optional feature wherein the rotor element and the stator element are each formed of a printed circuit board having conductive traces forming a first conductive pattern and a second conductive pattern, respectively.

Thereby, a displacement sensor for a power tool is achieved, wherein the stator element and the rotor element and the associated conductive elements can be manufactured in a cost-effective manner.

The displacement sensor is an optional feature, wherein the rotor element includes at least one capacitance configuration configured to provide noise suppression.

Thereby, a displacement sensor for a power tool is achieved, in which the noise affecting the intermediate signal can be effectively suppressed.

The displacement sensor is an optional feature wherein the rotor element comprises at least one capacitance layer forming at least one capacitor to provide noise suppression.

Thereby, a displacement sensor for a power tool is achieved, in which the noise affecting the intermediate signal is effectively suppressed and the capacitor, which is in the form of a capacitance layer, is protected from mechanical shock.

In addition, one or more of these objects can be achieved by a method of sensing the displacement between two relatively moving parts of the power tool. The method includes generating an excitation signal in the form of a high frequency excitation signal having a substantially constant amplitude. The method further includes providing an excitation signal to the first conductive pattern of the stator element. The method further comprises generating an intermediate signal in a second conductive pattern of the rotor element due to the mutual induction between the first conductive pattern and the second conductive pattern. The intermediate signal represents the relative displacement between the rotor element and the stator element.

Dependencies define optional features that correspond to those described in relation to the system.

The present invention will now be described in more detail with reference to the accompanying drawings, without restricting the description of the invention.
Figure 1 schematically illustrates a power tool with a rotary encoder according to an embodiment of the invention.
2 schematically shows a block diagram of a signal generating circuit according to an embodiment of the present invention.
Figure 3 schematically shows a top view of the stator of a rotary encoder according to an embodiment of the invention.
4 schematically shows a top view of a rotor of a rotary encoder according to an embodiment of the present invention.
5A schematically shows a waveform output from a rotor of a rotary encoder according to an embodiment of the present invention.
5B schematically shows waveforms output from a rotor of a rotary encoder according to an embodiment of the present invention.
6 schematically shows a block diagram of a signal processor circuit according to an embodiment of the present invention.
7A shows a flowchart of a method for sensing displacement between two relatively moving portions of a power tool according to an embodiment of the present invention.
Figure 7b shows a more detailed flowchart of a method for sensing displacement between two relatively moving parts of a power tool according to an embodiment of the present invention.

The drawings are schematic and simplified for brevity, and the drawings show only essential details in understanding the present invention, and others remain intact. Throughout the following detailed description, the same reference numerals are used for the same or corresponding parts or steps.

Referring to Figure 1, an electric power tool 1 with a displacement sensor in the form of an inductive rotary encoder 2 is disclosed in an embodiment of the present invention. The inductive rotary encoder 2 comprises a stator element 4 and a rotor element 3. The stator element 4 and the rotor element 3 are configured to be mounted concentrically around the axis A, such as being mounted concentrically around an axis extending in the axial direction of the shaft of the power tool 1. [ The stator element 4 and the rotor element 3 are further configured to be mounted at an axial distance AD with respect to one another. This means that an air gap is formed between the stator element 4 and the rotor element 3.

The stator element 4 is configured for attachment to a stationary portion (not shown) of the power tool 1. The stationary portion of the power tool may be a support structure or a housing for a moving part (not shown) of the power tool. An exemplary support structure or housing of the power tool 1 may be a support structure or housing for the moving part in the form of a rotatable shaft extending along the axis A, As shown in Fig. The rotor element 3 is configured to be attached to the moving part of the power tool 1, which is configured to attach to the rotatable shaft, as in the examples above. This means that the stator element 4 is stopped by being attached to the stationary part while moving in conjunction with the moving part by the attachment of the rotor element 3 to the moving part. Thus, when the moving part of the power tool 1 moves, the rotor element 3 will be moved relative to the stator element 4. When the rotor element 3 is attached to a rotatable shaft as in the above examples, the rotor element 3 will be angularly moved relative to the stator element 4 when the rotating shaft is moved.

The rotor element (3) and the stator element (4) are annular thin disk shaped. The rotor element and / or the stator element may further comprise at least one central aperture, such as a through hole, configured to accommodate at least one portion of the power tool 1, e.g., a shaft of the power tool.

The stator element 4 comprises a first conductive pattern or track CT1. More specifically, the first conductive pattern CT1 is formed in the stator element 4. The rotor element 3 comprises a second conductive pattern or track CT2. More specifically, a second conductive pattern CT2 is formed in the rotor element 3. The first and second conductive patterns CT1 and CT2 are formed in the stator element and the rotor element, respectively, in the radial direction RD. It is therefore preferred that the first and second conductive patterns CT1 and CT2 are located in the same radial direction RD and that the stator element 4 and the rotor element 3 are configured to be mounted concentrically around the axis A Therefore, the first and second conductive patterns CT1 and CT2 are configured to face each other through the air gap.

Preferably, the stator element 4 and the rotor element 3 are each electrically fabricated into a substrate such as an insulating substrate. More specifically, the stator element 4 and the rotor element 3 have a copper trace forming a conductive pattern with an associated electrical connector, that is, a conductive pattern having a conductive pattern printed on a PCB, (PCB). This provides excellent electrical insulation as well as excellent mechanical support for conductive patterns.

A more detailed description of the configuration of the first conductive pattern CT1 and the second conductive pattern CT2 will be described with reference to FIGS. 3 and 4, respectively.

The stator element 4 is driven, which means that it has at least one terminal or connector connected to a wiring ring (not shown) which is configured to be coupled to an energy source in the form of a signal generator 6. On the other hand, the rotor element 3 is passive, i.e. the rotor element 3 has no terminals or connectors with the associated wiring configured for connection to the energy source. Rather, when the first conductive pattern CT1 of the stator element 4 is energized, the first conductive pattern CT1 of the stator element 4 and the second conductive pattern CT2 of the rotor element 3 Due to the mutual inductance that occurs, the second conductive pattern of the rotor element 3 will receive energy.

The signal generation circuit 6 is configured to apply energy to the first conductive pattern CT1 of the stator 4 by generating a high frequency excitation signal SE having a substantially constant amplitude. The high frequency excitation signal is an alternating current (AC) signal. More details regarding the signal generating circuit will be described with reference to FIG. Between the first conductive pattern CT1 of the stator element 4 and the second conductive pattern CT2 of the rotor element 3 when the first conductive pattern CT1 is energized by the high frequency excitation signal SE, A current will be induced in the second conductive pattern CT2 because of the mutual inductance of the rotor element 3 and consequently the intermediate signal SI is formed in the second conductive pattern of the rotor element 3. [ If the rotor element 3 moves with respect to the stator element 4 the intermediate signal SI resulting in the induced current will be phase shifted or phase modulated with respect to the excitation signal SE and the stator element 4 and the rotor element 4, And information indicating the relative displacement between the first and second sensors 3 will be provided. This will be described in more detail with reference to Figs. 5A and 5B.

The stator element 4 is further configured to be coupled to the signal processor circuit 5. The signal processor circuit 5 is configured to receive the received signal SR which is transmitted from the rotor element over the air gap through the transmitting means and the receiving means of the rotor element 3 and the stator element 4 And an intermediate signal SI received at the stator element. The transmission of the intermediate signal SI from the rotor element to the stator element will not introduce any change in the intermediate signal SI which means that the received signal SR has substantially the same phase as the intermediate signal. The transmitting means and the receiving means will be described in more detail with reference to FIGS. 4 and 3, respectively. The signal processor circuit 5 is adapted to process the received signal SR to calculate and output information SOUT on the relative displacement such as the relative angular displacement between the rotor element 3 and the stator element 4 . The output information SOUT may be provided by the signal processor circuit 5 as a digital signal or an analog signal as a quadrature signal indicative of the relative displacement between the rotor element and the stator element. The processor circuit 5 is further configured to receive the reference signal SREF from the signal generating circuit 6. [ The signal processor circuit is configured to use the reference signal together with the processing of the received signal SR to provide output information. More details of the signals output by the signal processor circuit 5 and the signal processor circuit will be described with reference to FIG.

According to the embodiment, the signal processor circuit 5 is arranged to provide the output information SOUT in the form of an incremental signal.

According to the embodiment, the signal processor circuit 5 is configured to provide the output information SOUT in the form of an absolute signal.

According to an embodiment, the outer diameter of the stator element 4 and the rotor element 3 is configured to be selected in a spacing of 10-500 mm. For example, the outer diameter of the stator element 4 and the rotor element 3 may be selected to be about 40 mm.

The power tool 1 including the rotary encoder 2 can be an electric motor, a combustion engine or a power tool 1 driven by compressed air, for example, a pneumatic power tool. The power tool 1 may be a power tool selected from the group of power tools including a nut runner, a pulsating nut runner, a screwdriver, a range or a drill.

Referring to FIG. 2A, a signal generating circuit for a rotary encoder according to an embodiment of the present invention is shown.

The signal generation circuit 6 includes an AC power source 7, also referred to as an AC high frequency oscillator 7, configured to generate a high frequency signal AC1 with a substantially constant amplitude. The use of a signal having a substantially constant amplitude means that the smallest variations in amplitude, for example, due to performance constraints of the oscillator, or signals that exhibit small variations caused by noise affecting the signal, (AM) operation of the signal. The AC power source 7 includes a circuit for controlling the frequency of the high frequency signal AC1. The AC power source is configured to generate a high frequency signal (AC1) with a substantially constant amplitude (AMP) with a periodic waveform. The high frequency signal (AC1) generated by the AC power source has a frequency in the range of 100 KHz to 100 MHz.

According to the embodiment, the high frequency signal AC1 is generated as a sinusoidal waveform.

According to an embodiment, the high frequency signal AC1 produced by the AC power source has a frequency in excess of 100 KHz.

According to an embodiment, the high frequency signal AC1 produced by the AC power source has a frequency of more than 1 MHz.

According to the embodiment, the high frequency signal AC1 generated by the AC power source is periodic.

According to the embodiment, the high frequency signal AC1 is generated to have a single frequency such as a single frequency within the above-mentioned frequency range.

According to a preferred embodiment, the high frequency signal AC1 generated by the AC power source has a frequency in the range of 1 MHz to 10 MHz, for example 2.5 MHz. Preferably, the frequency of the high frequency signal AC1 is adapted to be removed from the frequency of other signals present in the vicinity of the power tool, such as a signal generated by a pre / magnetic configuration located inside or outside the power tool do. Thereby effectively reducing the influence of these signals on the sensing process. This also reduces the disturbances generated by the rotary encoder, which can affect other configurations inside or outside the power tool. According to a variant, spread spectrum modulation may be applied to the signal AC1 to further minimize the disturbance.

The signal generation circuit 6 includes a phase shifter circuit 8 coupled to the AC high frequency oscillator 7. [ The phase shifter circuit 8 is configured to receive the high frequency signal AC1 generated by the AC high frequency oscillator 7. [ The phase shifter circuit 8 is configured to generate and output a signal including a multi-phase signal, that is, a plurality of high frequency signals AC2 and AC3 each having a plurality of phases, based on the high frequency signal AC1. Preferably, the plurality of phases are different from each other.

In the example described with reference to Figure 2, the phase shifter circuit 8 is configured to generate and output two high frequency signals AC2 and AC3, where the high frequency signal AC3 is a high frequency signal AC2, I am in the office. The term "quadrature" is used to define that the signal AC3 is phase shifted with respect to the high frequency signal AC1. More precisely, the quadrature signal of the signal is separated by 90 ° (n / 2 or? / 4) in phase. Thus, the signal AC3 is phase-shifted by 90 degrees with respect to the high-frequency signal AC1. The quadrature circuit 8 is configured to output the quadrature signal AC3, and the quadrature circuit 8 is also configured to output the high frequency signal AC2 corresponding to the high frequency signal AC1, that is, without the phase shift.

It should also be noted that the phase shifter circuit 8 may be configured differently from the example described with reference to Fig. For example, the phase shifter circuit 8 may be configured to generate two or more high frequency signals having a plurality of phases, such as three or six high frequency signals each having a different phase, for example. In addition, the phase separation between the phases of the plurality of high frequency signals may differ from 90 degrees. For example, the phase shifter circuit 8 can generate and output three high frequency signals, one of which has a 0 DEG phase shift relative to the high frequency signal AC1, one of which is the high frequency signal AC1, Phase shift, one of which has a 240 [deg.] Phase shift relative to the high frequency signal AC1.

In addition, the phases of the plurality of high frequency signals generated by the phase shifter circuit need not form a geometric series, that is, a multiple of a constant phase shift.

2, the signal generation circuit 6 further includes two coil drive units 9 and 10 that are configured to be coupled to the phase shifter circuit 8. In this case, The first coil driver 9 of the two coil drivers is configured to receive the signal AC2. The second coil driver 10 of the two coil drivers is configured to receive the signal AC3. The first coil driver 9 is configured to generate and output a first excitation signal E1 and a second excitation signal E2. The second coil driver 10 is configured to generate and output the third excitation signal E3 and the fourth excitation signal E4. The first, second, third and fourth excitation signals form a multi-phase excitation signal, i. E., A plurality of excitation signals, each excitation signal having a phase of a plurality of phases, Is a phase-shifted phase from a predetermined number of angles AC1. The first excitation signal E1 is a high frequency signal having a substantially constant amplitude corresponding to the signal AC2. The second excitation signal E2 is a high frequency signal having a substantially constant amplitude corresponding to the phase shifted version of the signal AC2 where the second excitation signal E2 is phase shifted by 180 degrees relative to the signal AC2 do. The third excitation signal E3 is a high frequency signal having a substantially constant amplitude corresponding to the signal AC3. The fourth excitation signal E4 is a high frequency signal with a substantially constant amplitude corresponding to the phase shifted version of the signal AC3 where the fourth excitation signal E4 is phase shifted 180 degrees relative to the signal AC3 do. Thus, for the first excitation signal E1, the third excitation signal E3 is 90 ° phase shifted, the second excitation signal E2 is 180 ° phase shifted, and the fourth excitation signal E4 is 270 ° Phase shift. This means that the phases of the multi-phase signals comprising the first, second, third and fourth excitation signals are continuously increased by 90 ° in phase, i.e. 90 ° in the order of E1-E3-E2-E4 As shown in FIG. This is because the third excitation signal E3 is in the quadrature phase with the first excitation signal E1 and the second excitation signal E2 is in the quadrature phase with the third excitation signal E3, 4 excitation signal E4 is in quadrature phase with the second excitation signal E2. The two coil drivers of the signal generation circuit 6 may be differential amplifier circuits, and one of the two outputs may have the opposite polarity.

The signal generating circuit 6 provides the excitation signal in the form of a multi-phase excitation signal in a first conductive pattern of the stator element 4 so as to energize or excite the first conductive pattern of the stator element 4 To be connected to the stator element (4). More details on how the signal generated by the signal generating circuit 6 is propagated to the stator element will be described with reference to Fig.

Note that the signal generating circuit 6 illustrated with reference to FIG. 2 may be configured differently. For example, the signal generating circuit 6 may be configured to generate less or more output signals E1-E4 to be provided to the stator element 4. [ If the signal generation circuit is configured to produce fewer or more output signals than the illustrated example, i.e., the excitation signals (El-E4), the signal generator may include fewer or more coil drivers. As an example according to an embodiment of the present invention, the signal generating circuit includes one coil driver per generated excitation signal. According to an embodiment, the signal generating circuit is configured to generate and output an excitation signal having a 0 DEG phase, an excitation signal having a 120 DEG phase, and an excitation signal having a 240 DEG phase shift. In this embodiment, the signal generator includes three coil drivers, i. E., Generates an excitation signal per one. Further, the signal generation circuit 6 may include a power amplification circuit configured to amplify the signal output by the signal generation circuit 6.

Referring to FIG. 3A, a stator element of an inductive rotary encoder according to an embodiment of the present invention is described.

The stator element 4 of the rotary encoder, such as the rotary encoder 2, illustrated with reference to Figure 1, comprises a series of drive coils (SDC1-SDC8, ..., SDCk-3, SDCk-2, SDCk- , I.e., SDCl-SDCk), and a first conductive pattern, such as the first conductive pattern CT1. Thus, the series of drive coils includes k drive coils. The series of drive coils SDC1-SDCk are arranged equidistantly, that is, the distance between each drive coil of a series of drive coils and the adjacent drive coils is the same. A series of drive coils SDC1-SDCk are arranged on the stator element 4 along the circumferential direction of the stator element 4, such as arranged integrally with the annular disk-shaped stator element, . This means that a series of drive coils SDC1-SDCk are arranged to form a measurement path extending along the circumferential direction of the stator element 4. [ Each drive coil of a series of drive coils SDC1-SDCk is arranged on the stator element at a first predetermined radial distance RD1 from the center of the stator element 4, And extends outward to the radial distance RD2. Each of the drive coils of the series of drive coils SDC1-SDCk is arranged in a main extension direction aligned with the main extension direction of the stator elements, that is to say a plane formed in the main extension direction of the stator element 4, / RTI >

Each drive coil of a series of drive coils SDC1-SDCk includes a spiral or serpentine winding to form a loop arranged in a spiral pattern inward / outward. Preferably, the shape of the inner / outer helical pattern is configured such that the side of the helical pattern extending substantially along the radial direction of the stator element is substantially aligned with the radial direction of the stator element. That is, the side surface of the helical pattern, which is substantially straight, extending in the substantially annular direction of the stator element, has a curvature substantially matching the annular curvature of the stator element, Direction of the stator element is curved outwardly in the radial direction of the stator element so as to substantially match the curvature of the stator element. This also means that each segment of each side of the inner / outer helical pattern side that extends in the annular direction of the stator element is arranged at substantially the same radial distance from the center of the stator element. The winding has two end points, each of which is configured to be coupled to the terminal of the stator element 4. [ The winding of each drive coil of the series of drive coils SDC1-SDCk has a preset number of turns. Preferably, the predetermined number of turns in each winding is 2-5 turns.

Each of the drive coils of the series of drive coils SDC1-SDCk of the stator element 4, such as the drive coil SDC1, surrounds the area AR1 having a predetermined size. The region AR1 is freely configured in any form of a conductive element such as a winding.

The stator element 4 is configured to be coupled to a signal generating circuit, such as the signal generating circuit 6 illustrated with reference to FIG. 1 or FIG. The stator element 4 is configured to be coupled to a signal processor circuit, such as the signal processor circuit 5 illustrated with reference to FIG. 1 or FIG. More specifically, the stator element 4 is configured to be coupled to the signal generating circuit 6 and the signal processor circuit 5 via at least one input / output terminal M1. This allows the stator element 4 to be enabled to receive information in the form of an excitation signal SE, such as a multi-phase high frequency excitation signal having a substantially constant amplitude from the signal generation circuit 6, (SR) corresponding to the intermediate signal (SI) caused by the second conductive pattern (CT2) of the rotor element (3) by way of mutual induction, which is received via the receiving means , And is enabled to transmit information to the signal processor circuitry.

The stator element 4 further comprises a plurality of peripheries, i.e. terminals, two peripheral terminals with references PT1 and PT2 are shown in Fig. 3, arranged around the periphery of the stator element 4. Fig. These peripheral terminals are configured to provide or supply an excitation signal to each of the drive coils of the series of drive coils of the stator element 4.

Each drive coil of the series of drive coils SDC1-SDCk is configured with two terminals or leads shown in the circle in Fig. The two terminals at the end of each drive coil are configured to be coupled to the two terminals of the stator element 4. This is generated by the signal generating circuit 6, as illustrated by the high frequency excitation signal SE having the phase of the high frequency multi-phase excitation signal E1-E4, or more specifically with reference to FIG. 1 or FIG. To provide one of the excitation signals (E1-E4) with a particular phase to each drive coil.

According to a preferred embodiment, a series of drive coils SDC1-SDCk of the stator element 4 is configured to form a periodic repetitive phase pattern P1, which is repeated along the measurement path of the stator element 4. [ where n is an integer greater than or equal to zero and indicates the number of times the repeated phase pattern P1 along the measurement path of the stator element 4 is repeated. This means that a continuous plurality of drive coils (SDC1-SDCk), such as a consecutive predetermined number of drive coils of a series of drive coils of the stator elements, form a phase pattern, for example, The burn-in phase pattern P1 is followed by a series of drive coils arranged to include the phase patterns P1-Pn. By way of example, when n is zero, a series of drive coils SDC1-SDCk of the stator element 4 are configured to form a single-phase pattern P1 repeated zero times, i. E. A series of stator elements 4 The driving coils SDC1 to SDCk of the stator elements are arranged in the single-phase pattern P1 along the measuring path of the stator element. In another example, when n is 2, a series of drive coils (SDC1-SDCk) of the stator element 4 are configured to form a phase pattern P1 that repeats twice along the measurement path of the stator element 4 That is, the repeated phase pattern appears three times along the measuring path of the stator element 4, including the phase pattern P1 itself.

(E1-E4) of the multi-phase high frequency excitation signal SE having the high frequency multi-phase excitation signal SE or more specifically, the plurality of excitation signals E1-E4 ) Is supplied so that the adjacent drive coils of the phase pattern receive the phase of the high frequency multi-phase excitation signal SE phase-separated with respect to the neighboring drive coils of the phase pattern. It can also be expressed that the phase of the excitation signal to be supplied to the drive coil of the phase pattern is phase-shifted as the phase is increased in the continuous order of the drive coils forming the phase pattern.

In the example shown, four consecutive drive coils (SDC1-SDC4, SDC5-SDC8, ..., SDCk-3-SDCk) of a series of drive coils form a repeating phase pattern, That is, n is 7. More specifically, the drive coils SDC1-SDC4 form a phase pattern P1, the drive coils SDC5-SDC8 form a first period repeating phase pattern P2 of the phase pattern P1, drive coils (SDCk-3-SDCk) is hayeoseo form a phase pattern (Pn) is repeated n ^th -1 of the phase pattern (P1), a set of the drive coils, a phase pattern is periodically repeated, including P1 (P1) Lt; / RTI >

According to a preferred embodiment, the repeated phase pattern is a four-phase quadrature pattern which is repeated n times along the measuring path of the rotor element 3, such as seven iterations along the measuring surface of the rotor element 3 .

In this embodiment, a four-phase quadrature pattern is configured so that four consecutive drive coils forming a four-phase quadrature pattern have 0 DEG phase, 90 DEG phase, 180 DEG phase and 270 DEG phase Phases of the multi-phase excitation signal are provided, respectively. This will be achieved by supplying an excitation signal having a 0 [deg.] Phase, such as the excitation signal E1 illustrated with reference to Fig. 2, to the first drive coil SDC1 in the order of the 4-phase quadrature pattern, An excitation signal having a 90-degree phase such as the excitation signal E3 illustrated with reference to Fig. 2 will be supplied to the drive coil SDC2, which is the second in the order of the phase quadrature pattern, The drive coil SDC3, which is the third in the order of the patterns, will be supplied with an excitation signal having a phase of 180 [deg.] Like the excitation signal E2 illustrated with reference to Fig. 2, and in the order of the 4-phase quadrature pattern The fourth excitation coil SDC4 is supplied with an excitation signal having a 270 phase such as the excitation signal E2 illustrated with reference to Fig. In the case where the rotary encoder 2 is configured to sense the rotational displacement of the shaft of the electric motor of the power tool, the number of four-phase quadrature patterns, i.e. the period, is preferably synchronized with the number of cycles of the electric motor .

In another embodiment, the periodically repeated phase pattern P1 is provided in a three-phase pattern. The three-phase pattern is formed by three consecutive drive coils of a series of drive coils (SDC1-SDCk). The 3-phase pattern is arranged to repeat n times. So that excitation signals having a phase of 0 DEG, such as the excitation signal E1 exemplified with reference to Fig. 2, are supplied to the first drive coil SDC1 in the sequence of three consecutive drive coils forming the three-phase pattern Arranged to be supplied with an excitation signal having a phase of 120 ° to the second drive coil SDC2 in the order of three consecutive drive coils forming a three-phase pattern, and three And an excitation signal having a phase of 240 [deg.] Is supplied to the driving coil SDC3, which is the third in the sequence of the continuous driving coils.

It should be noted that any number of consecutive drive coils of a series of drive coils SDC1-SDCk may be arranged to form a periodic repetitive phase pattern P1. Each excitation coil included in the periodically repeated phase pattern can be arranged to be supplied with excitation signals having different phases from the excitation signals exemplarily, depending on the various excitation signals, i.e. the application and configuration of the signal generation circuit .

The stator element 4 according to the embodiment further comprises receiving means in the form of a balanced receive coil (SRC). The balanced receiving coil SRC receives a received signal SR which is a signal corresponding to the signal transmitted from the transmitting means of the rotor element 3 which is transmitted to the second conductive pattern of the rotor element 3 CT2, i. E. An intermediate signal SI as illustrated with reference to Fig. The transfer means of the rotor element 3 will be described in more detail with reference to Fig. More precisely, the balanced receiving coil (SRC) of the stator element (4) comprises two balanced receiving coil sections in the form of a first balanced receiving coil section (SRCA) and a second balanced receiving coil section . The first and second balanced receiving coil sections are configured such that the currents induced in each of the first and second balanced receiving coil sections flow in opposite directions with respect to each other. This means that the current induced in the first balanced receive coil section SRCA flows in the opposite direction to the current induced in the second balanced receive coil section SRCB. The first balanced receiving coil section SRCA is configured to be arranged concentrically about the center of the stator element 4 at the third radial distance RD3. The second balanced receiving coil section SRCB is configured to be concentrically arranged around the center of the stator element 4 at the fourth radial distance RD4. The first and second balanced receiving coil sections SRCA and SRCB are each in the form of a spiral or serpentine winding with an annular shape.

The winding of the drive coil of the stator element 4 is preferably made of copper or other suitable material with a conductive characteristic. The conductor width of the winding may be about 12 탆.

According to an embodiment, the outer diameter of the stator element 4 is selected in the range of diameters including 10-500 mm, such as 40 mm.

It should be noted that the stator element 4 illustrated with reference to Fig. 3 is similar to that described with reference to Fig. 1, and also that the stator element 4 is preferably made of an electrically insulating substrate such as a PCB.

Referring to Figure 4, a rotor element of an inductive rotary encoder according to an embodiment of the present invention is described.

The rotor element 3 of an inductive rotary encoder, such as the inductive rotary encoder 2 illustrated with reference to Figure 1, comprises a series of receiving coils (RRC1, RRC2, ..., RRCi, i.e., RRC1-RRCi) And a second conductive pattern, such as the first conductive pattern CT2. Thus, the series of receive coils RRC1-RRCi of the rotor element 3 includes i receive coils.

The series of receiving coils RRC1-RRCi are arranged equidistantly, that is, the distance between each receiving coil of a series of receiving coils and the adjacent receiving coil is the same. A series of receiving coils RRC1-RRCi are arranged in the rotor element 3 along the circumferential direction of the rotor element 3, such as is arranged integrally with an annular disk-shaped rotor element, . This means that a series of receiving coils RRC1-RRCi are arranged to form a measuring path extending along the circumferential direction of the stator element 4. [

Each receiving coil of the series of receiving coils RRC1-RRCi is arranged on the rotor element at a first predetermined radial distance RD1 from the center of the rotor element 3, And extends outward to the radial distance RD2. The first and second radial distances at which the receiving coils extend coincide with the first and second radial distances at which the driving coils of the stator element 4, such as the stator element illustrated with reference to Fig. 3, extend.

Each receiving coil of the series of receiving coils RRC1-RRCi is arranged in a main extending direction aligned with the main extending direction of the rotor element 3, i.e. extending in a plane formed in the main extending direction of the rotor element 3 Lt; / RTI > This means that the second conductive pattern CT2 of the rotor element 3 or the measuring path is preferably configured to face the first conductive pattern CT1 or measurement path of the stator element 4. [

Each receiving coil of a series of receiving coils RRC1-RRCi, such as the receiving coil RRC1 of the rotor element 3, comprises a winding with spiral or serpentine winding, Form a separate balanced, loop element, referred to as L2. The two loop elements of each receive coil (RRC1-RRCi) are intertwined by the winding going between the two loop elements. The receiving coil RRC1 includes two balanced entangled loop elements RRC1: L1 and RRC1: L2, respectively, and the receiving coil RRC2 comprises two balanced entangled loop elements RRC2: L1, RRC2: L2 An example involving is shown in FIG. Each of the two loop elements is further arranged in an inner / outer helical pattern similar to a spiral pattern into / out of the drive coils (SDC1-SDCk) of the stator element 4 illustrated with reference to Figure 3, And is configured to include a pattern having a curved side section and a straight side section, respectively. The windings have two end points with associated ends, each of which is configured to be coupled to the terminals of adjacent windings, i.e., adjacent receiver coils of the rotor element 3. Thus, the series of receiving coils RRC1-RRCi of the rotor element 3 are configured to be connected in series.

The winding of each of the receiving coils of the series of receiving coils RRC1 to RRCi has a predetermined number of turns. Preferably, the predetermined number of turns in each winding is 2-5 turns.

Each loop element of each receiving coil of a series of receiving coils RRC1-RRCi of the rotor element 3, such as the receiving coil RRC1, surrounds the areas A1: 1, A1: 2, And has a predetermined size that is freely configured in the form of any conductive element, such as a winding. More specifically, a first loop of each winding, i. E. The receiving coil of the rotor element 3, surrounds the area A1: The loop surrounds the area A1: 2.

Each receiving coil of the series of receiving coils RRC1-RRCi of the rotor element 3 is connected to the rotor element 3 of the first and second loop elements of each receiving coil of the series of receiving coils RRC1- The extension in the plane formed in the main extending direction of the stator element 4 coincides with the extension of two adjacent driving coils of the series of driving coils SDC1-SDCk of the stator element 4. [ This means that each loop element which is the first and second loop elements of the respective receiving coils of a series of receiving coils RRC1 of the rotor element 3 is connected to a series of driving coils SDC1 to SDCk of the stator element 4. [ Lt; RTI ID = 0.0 > of the < / RTI > two adjacent drive coils of the first drive coil.

Furthermore, between each of the two loop elements of the respective receiving coils of the series of receiving coils (RRC1-RRCi) of the rotor element 3, the distance along the measuring path of the rotor element 3 and the distance The distance along the measuring path of the rotor element 3 between each of the receiving coils of the stator element 4 and between the respective receiving coils of the stator elements 4, RRC1, RRC1, Correspond to distances. This means that when the rotor element 3 moves along the measuring path of the rotor element 3, each loop element of each receiving coil of the series of receiving coils of the rotor element 3, Quot; means that it will periodically face two adjacent drive coils of drive coils SDC1-SDCk.

The direction of winding in the first loop element and the second loop element which combine the respective windings, which are the receiving coils of the rotor element 3, is repeated i-1 times along the measuring path of the rotor element 3 Phase pattern, where i is an integer in the range of one or greater. This means that when i is equal to 1, only receiving coils RRC1 forming an alternating 2-phase pattern are present along the measuring path of the rotor element 3 and i is equal to 3, the receiving coils RRC1 , RRC2 and RRC3 are present along the measurement path of the rotor element 3 so that the repeated two-phase pattern is repeated twice in the form of RRC2 and RRC3, separate from the two-phase pattern formed by the receiving coil RRC1 . More specifically, the first and second loop elements of each of the adjacent loop elements, i. E., The receive coils of a series of receive coils (RRC1-RRCi) are configured in anti-phase, i.e., 180, in phase. This means that adjacent loop elements in the form of a first loop element of the second loop element of the receive coil and a series of receive coils RRC1-RRCi are anti-phase. Also, adjacent loop elements in the form of a first loop element of the receive coil and a second loop element of the previous receive coil of the series of receive coils are anti-phase. Due to the alternating two-phase pattern, the effect of electromagnetic interference, which is a form of alternating electromagnetic fields of a common background, due to the current induced by the alternating electromagnetic fields of the common background in adjacent loop elements, Will be offset. This will not be the case for the current induced by providing an excitation signal to the first conductive pattern because the configuration of the excitation signal and the respective loop elements of the receiving coil by the first conductive pattern of the stator element have different phases Will be induced by the exciting current. The rotor element 3 according to the embodiment further comprises transfer means in the form of a balanced drive coil (RDC). According to this embodiment, the stator element 4 consists of receiving means in the form of balanced receiving coils, as will be explained in more detail with reference to Fig. The balanced drive coil RDC of the rotor element 3 is adapted to be coupled to the second conductive pattern CT2 of the rotor element 3 such that the intermediate signal SI is applied to the first conductive pattern Such that the intermediate signal is propagated into the balanced drive coil of the rotor element 3 when the signal is generated in the second conductive pattern of the rotor element 3 due to the application of the energy, Is generated in the balanced receive coil (SRC) of the element (4).

More specifically, the balanced drive coil (RDC) of the rotor element (3) comprises two balanced drive coil sections (RDCB) in the form of a first balanced drive coil section (RDCA) and a second balanced drive coil section . The first and second balanced drive coil sections are configured such that the currents induced in each of the first and second balanced drive coil sections flow in opposite directions with respect to each other. This means that the current induced in the first balanced drive coil section RDCA flows in the opposite direction to the current induced in the second balanced drive coil section RDCB. The first balancing drive coil section RDCA has a third radial distance RD3, i.e. the radius of the first balanced received section SRCA of the stator element 4, such as the stator element illustrated with reference to Figure 3, Are arranged concentrically about the center of the rotor element 3 at a distance equal to the distance. The second balancing drive coil section RDCB is located at a distance equal to the fourth radial distance RD4, i.e. the radial distance of the second balanced receiving coil section SRCB of the stator element 4, As shown in FIG. This is because the first balanced drive coil section RDCA of the rotor element 3 is arranged to face the first balanced received coil section SRCA of the stator element 4 and the second balanced drive coil section SRCA of the rotor element 3 A balanced drive coil section RDCB is arranged to face the second balanced receive coil section SRCB of the stator element 4 so that when energy is applied to the balanced drive coil RDC of the rotor element 3 Which means that mutual inductance occurs. This means that when the balanced drive coil RDC and thereby the balanced drive coil sections RDCA and RDCB of the rotor element 3 are energized by the intermediate signal SI, Due to the mutual inductive coupling between the balanced drive coil sections RDCA and RDCB of the rotor element 3 and the balanced receive coil sections SRCA and SCRB of the stator element 4, ) Balanced receiving coil sections SRCA, SRCB. This is because the signal, i.e. the received signal SR, is generated in the balanced receive coil SRC of the stator element 4, which corresponds to the transmitted intermediate signal SI, Balanced reception coil (RDC) and a balanced reception coil (SRC) of the stator element 4, respectively.

According to an embodiment, the rotor element 3 comprises a series of receiving coils RRC1 - RRCi, a balanced drive coil RDC with balanced drive coil sections RDCA, RDCB and at least one capacitor arrangement Lt; RTI ID = 0.0 > (LC) < / RTI > bandpass filter. The LC bandpass filter is configured to have a center frequency substantially equal to the frequency of the high frequency excitation signal (E1-E4). The at least one capacitor arrangement is adapted to provide attenuation of the band noise filtered by the filter characteristic of the LC bandpass filter.

According to an embodiment, the rotor element 3 comprises at least one capacitance layer (not shown) embedded in the rotor element 3 using an embedded capacitance material (ECM). With a series of receiving coils (RRC1-RRCi) and balanced drive coils (RDC), at least one of the capacitance layers forms the LC bandpass filter mentioned above. Since the filtering capacitor function is embedded in the rotor element 3 in the form of at least one capacitance layer, the risk of mechanical damage due to stress or handling is greatly reduced.

According to an embodiment, the outer diameter of the rotor element 3 is selected in the range of diameters including 10-500 mm, such as 40 mm.

It should be noted that the rotor element illustrated with reference to FIG. 3, similar to that described with reference to FIG. 1, is preferably made of an electrically insulating substrate such as a PCB.

Referring to Figure 5A, the waveforms produced in the conductive pattern of the rotor element are described when there is relative movement between the stator element and the rotor element in accordance with an embodiment of the present invention.

5A shows a linear configuration of a stationary stator element 4 having a first conductive pattern in the form of a series of drive coils SDC1-SDCk, along with a series of receive coils RRC1- Lt; / RTI > shows a linear configuration of a relatively moving rotor element 3 having a second conductive pattern in the form of a first conductive pattern RRCi. The rotor element 3 moves reciprocally with respect to the stator element 4 in the direction MV. Thus, Figure 5a shows a linear inductive encoder with a waveform output from a linear inductive encoder if the rotor element moves linearly relative to a stationary stator element. However, for an output waveform, if there is a relative movement of the rotor elements, the same principle applies to the linear and rotary encoders.

For purposes of illustration, only a portion of the rotor element and the stator element are shown in Figure 5A. A portion of the rotor element shown in Figure 5A comprises two consecutive receiving coils RRC1-RRC2 of a series of receiving coils of the rotor element 3, each of the two receiving coils RRC1- (RRC1: L1, RRC1: L2 and RRC2: L1, RRC2: L2), respectively, as illustrated with reference to FIG. A portion of the stator element shown in Figure 5adp includes eight consecutive drive coils (SDC1-SDC8) of a series of receive coils (SDC1-SDCk) of the stator element 4. [

The excitation signal SE shown in Fig. 5A provided from the signal generation circuit 6 illustrated in more detail with reference to Fig. 2, in the example described with reference to Fig. 5A, is a multi-phase high frequency As the excitation signal SE, each has a substantially constant amplitude and a predetermined number of phases. More specifically, the multi-phase high frequency signal SE includes a high frequency excitation signal E1 with a 0 degree phase, a high frequency excitation signal E3 with a 90 degree phase, a high frequency excitation signal E2 with a 180 degree phase, And a high-frequency excitation signal E4 having a 270 [deg.] Phase.

In the example with reference to Fig. 5a, the series of drive coils of the stator element comprises four consecutive drive coils, arranged in a periodically repeated phase pattern P1. This means that the first, second, third and fourth drive coils form a repetitive phase pattern P1 in successive sequences (SDC1-SDC4), which is the first iteration in the form of drive coils (SDC5-SDC8) (P2).

The excitation signals E1-E4 of the multi-phase excitation signal SE are adapted to be provided to the drive coils of the stator element in the example with reference to Figure 5a so that each repetition of the repetitive phase pattern P1 The excitation signal E1 is supplied to the first driving coils SDC1 and SDC5 which are the first in the continuous sequence of the repetitive phase patterns P1 and P2, The excitation signal E3 is supplied to the second drive coils SDC2 and SDC6 and the third drive coils SDC3 and SDC3 which are the third in the sequence of each repetition P1- The excitation signal E2 is supplied to the fourth drive coils SDC4 and SDC8 and the fourth drive coils SDC4 and SDC8 which are fourth in the sequence of the repetitions P1 to P2 of the repetitive phase patterns P1, .

In the example described with reference to Fig. 5A, the rotor element has a first and a second loop (RRC1: L1, RRC1: L2, RRC2: L1, RRC2: L2) of each of the illustrated receive coils RRC1, RRC2 Is positioned relative to the stator element to face two successive drive coils of the stator element. More specifically, the first loop RRC1 (L1) of the first receiving coil RRC1 faces the first and second continuous driving coils SDC1 and SDC2, respectively, and the first receiving coil RRC1 The first loop RRC2: L1 of the second receiving coil RRC2 faces the third and fourth consecutive driving coils SDC3 and SDC4, respectively, while the second loop RRC2: And the second loop RRC2: L2 of the second receiving coil RRC2 faces the seventh and eighth consecutive driving coils SDC7 and SDC8, respectively. The first and second receiving coils are positioned overlapping with their respective driving coils so that the first and second receiving coils RRC1 and RRC2 having the display numbers L1 and L2 of the respective receiving coils RRC1 and RRC2, The loop element faces two consecutive drive coils, i.e. each receive coil is centered on the top of four consecutive drive coils.

As described above, the excitation signal SE is provided to the series of drive coils of the stator element such that the current between the drive coil of the stator element and the receive coil of the rotor element is induced in the receive coil of the rotor element, Resulting in the intermediate signal SI being formed in the receiving coil of the rotor element 3. [ This intermediate signal will then be transmitted from the balanced drive coil of the rotor element to the balanced receive coil of the stator element, as will be described in more detail with reference to Fig. As a result, the received signal SR corresponding to the intermediate signal SI is generated in the stator element, that is, in the balanced receiving coil of the stator element. Due to the configuration of the previously described stator element and rotor element and the multi-phase excitation signal and the intermediate signal, therefore, the received signal SR will have a phase corresponding to the sum of the phases of the multi-phase excitation signal. The phase of the received signal SR will be phase shifted, with the rotor element moving relative to the stator element, i.e., the phase of the received signal, based on the relative position between the rotor element and the stator element, (SRM) for each of the high-frequency excitation signals of the high-frequency signal SE.

Thus, for example, the phase of the received signal (SR) for any one phase of the high frequency excitation signal of the multi-phase excitation signal will represent the relative displacement between the rotor element and the stator element, with respect to the angular displacement expressed in terms of the electrical angle . The angular displacement expressed in electrical angles can be translated into a machine angle using information on the number of periodically repeated phase patterns arranged at least along the measurement path of the stator element. Each iteration of the periodically repeated phase pattern forms an electrical period. Thus, the electrical period is transformed into a portion of the total mechanical rotation of the rotor element relative to the stator element, where the fraction is determined by the number of electrical periods, i.e. the number of periodic iterations of the periodically repeated phase pattern.

5A, the rotor element is positioned relative to the stator element such that the received signal SR is 45 DEG phase shifted relative to the high frequency excitation signal E1 of the multi-phase high frequency excitation signal SE, That is, the phase difference PD is set to 45 degrees. This ensures that the rotor element is positioned relative to the stator element such that the first loop (RRC1: L1) of the receiving coil RRC1 of the rotor element is positioned at 45 [deg.] With respect to the center of the driving coil SDC1, As illustrated, the center of the first loop means that it is located between the drive coil SDC1 and the drive coil SDC2. This means that when the center of the first loop RRC1: L1 is aligned with the center of the drive coil SDC1, i.e. when the first loop RRC1: L1 is centered on the top of the SDC1, The received signal SR is in phase with the excitation signal E1, that is, the phase between E1 and SR (i.e., the phase between E1 and SR) The difference (PD) is 0 degrees. The previously detected phase difference may be used to determine whether the rotor has moved relative to the stator element, or whether the rotor is stationary or temporarily in the stop position. By way of example, if the previous phase difference is a 0 electrical angle and the current phase difference is 45 electrical degrees, then the rotor element may conclude that it moved at an electrical angle of 45 relative to the stator element. In order to detect the reciprocating motion of the rotor element relative to the stator element, an increase or decrease in the phase shift is used in relation to the previously determined phase shift.

For example, if the stator element includes six iterations of the periodic repeating phase pattern P1, i.e., the repeating phase pattern P1 appears seven times along the measuring path of the stator element, including P1 itself, The progression of the phase difference from 0 DEG to 360 DEG, i.e. from 0 DEG to 0 DEG, will correspond to a relative angular displacement of 360 DEG from the electrical angle, which corresponds to the seventh portion of the total mechanical rotation of the rotor element relative to the stator element Relative angular displacement.

The resulting waveforms described above with respect to the received signal SR due to energization using a multi-phase high frequency excitation signal SE dependent on the relative position of the rotor element and the stator element are also shown in Figure 5b, , The rotor element 3 moving relative to the linear configuration of the stationary stator element 4 in a manner similar to that described with reference to Figure 5a, wherein the stator element, the rotor element and the excitation signal refer to Figure 5a Lt; / RTI > However, in Figure 5b, the rotor element moved 135 ° electrical angle relative to the stator element. This can be seen by having the received signal SR have a phase shift of 135 °, i.e. having a phase difference PD of 135 ° with respect to the phase of the high frequency excitation signal E 1 of the multi-phase high frequency signal SE . More specifically, the rotor element 3 shown in Figure 5b moves relative to the stator element 4 so that the first loop RRC1 (L1) of the first receiving coil RRC1 is driven by the second and third consecutive drives The second loop RRC1: L2 of the first receiving coil RRC1 faces the fourth and fifth continuous driving coils SDC4 and SDC5, respectively, and the second reception The first loop RRC2 of the coil RRC2 faces the sixth and seventh consecutive driving coils SDC6 and SDC7 and the second loop RRC2 L2 of the second receiving coil RRC2 Eighth and ninth consecutive drive coils SDC8 and SDC9, respectively.

It should be noted that the rotor element and / or the stator element may be configured differently from the example described with reference to Figures 5A and 5B. For example, the number of drive coils included in the repeated phase pattern may include more or less drive coils. Different excitation signals may be provided for each drive coil. By way of example, the repeated phase pattern may include three consecutive drive coils, which are supplied in 0 占 phase, 120 占 phase, and 240 占 phase in a continuous sequence of drive coils or repeating phase patterns. Further, another signal other than the signal E1 may be used as the reference signal, for example, any of the signals E1-E4 may be used. In addition, variations may include, for example, one or more features described in conjunction with one or more of the other embodiments described above with reference to Figures 1-4.

It should be further noted that the example described with reference to Figures 5a and 5b shows only a portion of the rotor element and the stator element in the linear layout, respectively. Thus, the rotor element and the stator element can be configured in an annular fashion to provide a rotary displacement sensor. In addition, the rotor element may include more receiver coils than shown in Figures 5A and 5B, and the stator element may include more drive coils than those shown in Figures 5A and 5B. Further, depending on the configuration of the stator element and the rotor element, for example, related to the number of drive coils / receiver coils and the number of drive coils included in the repeated phase pattern Pl, the mechanical rotation of the rotor element relative to the stator element The number of electrical charge cycles can be different, for example, if only the phase pattern P1 itself appears along the measurement path of the stator element, if the repeated phase pattern is repeated 0 times, i.e. without repeating P2, P3, The corresponding number of electrical cycles per mechanical rotation of the rotor element for the stator element will be one.

6A, a signal processor circuit for an inductive rotary encoder according to an embodiment of the present invention is described.

The signal processor circuit 5 is configured to couple to a stator element such as the stator element 4 illustrated with reference to Fig. 1 or Fig. More specifically, the signal processor circuit 5 is configured to couple to the stator element via at least one main terminal, such as at least one main terminal M1 illustrated with reference to Fig.

The signal processor circuit 6 receives the received signal SR corresponding to the intermediate signal SI derived from the second conductive pattern CT2 of the rotor element when the first conductive pattern of the rotor element 3 is excited . More specifically, as will be described in more detail with reference to Figures 3 and 4, the received signal SR is transmitted from the rotor element and corresponds to the intermediate signal SI received by the stator element.

The signal processor circuit 6 is further configured to receive a reference signal SREF corresponding to one of the excitation signals E1-E4 of the excitation signal SE or more specifically the multi-phase excitation signal SE . It should also be understood that any of the excitation signals E1-E4 of the multi-phase excitation signal can be used as the reference signal SREF.

The signal processor 5 includes a differential preamplifier circuit 11 provided to amplify the received signal SR so as to provide an amplified signal SI based on the received signal SR. The preamplifier circuit is connected to the bandpass filter circuit 12 included in the signal processor circuit and supplies the amplified signal SI as an amplified version of the received signal SR to the bandpass filter circuit 12 send.

The band pass filter circuit is configured to have a center frequency substantially equal to the frequency of the excitation signal SE generated by the signal generation circuit 6. [ This means that the frequency component near the bandpass filter circuit center frequency will be passed to the output of the bandpass filter circuit and the remaining frequency components will be reduced, i.e. substantially filtered. Therefore, the main frequency component of the amplified signal SI received by the band-pass filter circuit having a frequency near the frequency of the excitation signal SE will be output by the band-pass filter circuit, but the remaining frequency components are very attenuated will be.

The bandpass filter circuit 12 is further provided to be coupled to the phase detection circuit 13 for providing a filtered signal S2 which is applied to the bandpass filter < RTI ID = 0.0 > (12). ≪ / RTI >

The phase detection circuit 13 is configured to receive the above-mentioned filtered signal S2 and the reference signal SREF.

The phase detection circuit is composed of a demodulator and a decoder. The phase detection circuit 13 is configured to operate using a reference signal having a phase relation corresponding to a known frequency and an excitation signal SE. More specifically, the phase detection circuit is configured to detect and output the phase difference between the reference signal SREF and the filtered signal S2, wherein the phase difference detected and output by the phase detection circuit is determined by the phase difference between the stator element 4 ) And the rotor element (3).

Preferably, the phase detection circuit 13 detects the phase difference between the received signal SR and the excitation signal SIRF, described with reference to FIG. 1, based on the received reference signal SREF and the filtered signal S2. Phase / quadrature (I / Q) demodulator (I / Q) demodulator that generates and outputs information OUT in the form of two quadrature signals I1 and Q1, respectively, Or an I / Q decoder circuit. Preferably, the I / Q demodulator further comprises at least one low-pass filter that provides low-pass filtering to suppress signal variation of the I1 and Q1 signals, respectively. Low pass filtering increases the accuracy of displacement sensing by filtering the high frequency excitation signal.

The I / Q demodulation circuit may comprise, for example, two demodulators, one of which produces an in-phase signal I1, one of which produces a quadrature-phase signal Q1. A demodulator configured to generate an in-phase (I1) signal may be operated using a 0 [deg.] Phase and a demodulator configured to generate a quadrature-phase signal (Q1) may be operated using a 90 [deg.] Phase.

The signal processor circuit 5 may further include an analog-to-digital converter (ADC) The ADC 14 is configured to receive the signal output from the phase detection circuit 13 and to couple to the phase detection circuit to provide an analog-to-digital conversion of the signal received from the phase detection circuit 13. [ The ADC 14 may be configured as a 12-bit ADC, or it may be configured to operate using different bit resolutions depending on the application. Thus, the ADC 14 is configured to output a digitized version (I2, Q2) of the received signal (I1, Q1) as an input.

It should be noted that the signal processor circuit described above can be configured differently from the signal processor described with reference to Fig. For example, the signal processor circuit may include more or less configurations such as filters and amplifiers.

In order to clearly determine the resulting relative displacement D between the rotor element 3 and the stator element 4, an inverse tangent function, i.e. an "arctangent" function may be used, given by equation (1) .

In equation (1), (1) item I1 is the in-phase signal I1, and item Q1 is the quadrature-phase signal Q1 output by the phase detection circuit 13. More specifically with respect to equation (1), the relative displacement (D) is derived differently depending on whether the absolute value of the I1 signal is greater than the absolute value of the signal (Q1). Since the expression relating to how the relative displacement D is derived is included in equation (1), the arc tangent function provides a single value for a parameter in the range of 0 [deg.] To 90 [deg.], It is a condition that can derive a single value of D independent of the value. The in-phase and quadrature signals I1 and Q1 can be expressed by the following equations 2 and 3, respectively.

The term fc in equations (2) and (3) represents a signal in phase with a signal used for SREF, such as E1, which has the same frequency as SREF. In the equations (2) and (3) associated with the in-phase signal I1 and quadrature signal Q1, respectively, the term SR may be expressed, for example, in any of Figures 1, 5a, 5b and 6, And displays the received signal SR. Thus, the received signal SR, when provided in the first conductive pattern CT1 of the stator element, is generated by the phase sum of the excitation signal induced in the second conductive pattern CT2 of the rotor element 3, And corresponds to the signal SI. In equations (2) and (3), the term t denotes time. As described above, the four-phase pattern can be divided into four excitation signals, one for the 0 DEG phase, one for the 90 DEG phase, one for the 180 DEG phase and one for the 270 DEG phase When energized by the excitation signal and executed, the received signal SR is given by equation (4).

는 전기 주기 내의 스테이터 요소와 로터 요소 사이의 각변위, 즉, 상기 기술된 주기적으로 반복되는 위상 패턴 P1의 주기 내의 스테이터 요소와 로터 요소 사이의 각변위를 나타낸다. 도 3 및 도 4를 참조하여 예시된 스테이터 요소와 로터 요소에서, 스테이터 요소에 대해 로터 요소의 각각의 전체 기계적 회전에 대한 7개의 전기적 주기가 있는데, 즉, 주기적으로 반복되는 위상 패턴은 7번 반복된다.In equation (4), the term AD denotes the distance between the stator element 4 and the rotor element 3 and is also referred to as the axial distance AD as exemplified with reference to Fig. The term in equation (4)

Represents an angular displacement between the stator element and the rotor element in the period of the electric cycle, i.e., the angular displacement between the stator element and the rotor element in the period of the above-described periodically repeated phase pattern P1. In the stator element and the rotor element illustrated with reference to Figures 3 and 4, there are seven electrical cycles for each total mechanical rotation of the rotor element relative to the stator element, i.e., the periodically repeated phase pattern is repeated seven times do.

에 종속하는 함수 f 이다.Thus, the received signal SR is dependent, i.e. the configuration of the multi-phase excitation signal, the distance AD between the rotor element and the stator element, and the angular displacement between the aforementioned stator element and rotor element

Is a function f that depends on.

, Q1 및 I1은 시간 t에 종속적이다. 로터 요소가 일시적 정지 위치와 같은 정지 위치에 있을 때가 아니라, 로터 요소가 움직이는 경우에, 항

만 시간 t에 따라 가변한다는 것에 유의한다.It should be noted that the various terms in equations (1) to (4) are time-dependent, i.e., time-dependent. By way of example, the terms E1-E4,

, Q1 and I1 depend on time t. When the rotor element moves, not when the rotor element is at the same stop position as the temporary stop position,

Note that it only varies with time t.

Referring to FIG. 7A, there is provided a description of a flowchart of a method for sensing displacement between two relatively moving portions of a power tool, using an inductive rotary encoder, in accordance with an embodiment of the present invention.

In a first method step SlOO, a high frequency excitation signal is generated. Advantageously, a high frequency excitation AC signal having a substantially constant amplitude is generated by a signal generating circuit coupled to the stator element. Preferably, the high frequency signal generated by the signal generating circuit is a multi-phase high frequency excitation signal comprising a plurality of phases, i.e. the multi-phase high frequency signal is a signal of a plurality of phases And a plurality of high frequency excitation signals each having a phase. The signal generating circuit is preferably configured as described with reference to Fig. After step S100, a subsequent method step S110 is performed.

In method step S110, a high frequency AC signal is provided in the first conductive pattern of the stator element. The high frequency AC signal provided to the first conductive pattern of the stator element is further configured to have a substantially constant amplitude. More specifically, a signal generator, such as the signal generator 6 illustrated with reference to FIG. 2, for generating a high frequency AC excitation signal is configured to couple to a peripheral terminal of the stator element, Such as to be coupled to the first conductive pattern illustrated with reference to the first conductive pattern < RTI ID = 0.0 > CT1. ≪ / RTI > This means that the signal generator 6 can provide the high frequency AC excitation signal to the first conductive pattern of the stator element. After method step S110, thereafter, method step S120 is performed.

In method step S120, an intermediate signal is generated within the second conductive pattern CT2 of the rotor element. More specifically, an intermediate signal, such as the intermediate signal SI illustrated with reference to FIG. 1, is generated by the first conductive pattern of the stator element and the second conductive pattern of the rotor element, Such as the rotor element 3 illustrated with reference to FIG. The intermediate signal SI represents the relative displacement between the rotor element and the stator element. After method step S120, the method ends.

Figure 7b shows a more detailed embodiment of a method for forcing a displacement between two relatively moving parts of a power tool using an inductive rotary encoder.

The method according to the present embodiment includes three method steps S200, S210 and S220 to be performed continuously. The method steps S200, S210 and S220 correspond to the method steps S100, S110 and S120 respectively described with reference to Fig. 7A. Referring to FIG. 7B, after method step S220, method step S230 is performed. In method step S230, the intermediate signal SI is transmitted from the rotor element 3. More specifically, the intermediate signal is transmitted from the rotor element 3 using a balanced drive coil (RDC) as illustrated with reference to Fig. A balanced drive coil (RDC) of the rotor element (3) is configured to engage the second conductive pattern of the rotor element (3). This constitutes a balanced drive coil (RDC) of the rotor element 3 such that when a current is induced in the second conductive pattern CT2 of the rotor element 3 and the excitation signal is provided, The resulting intermediate signal SI of the rotor element CT2 will be provided to the balanced drive coil RDC of the rotor element 3. [ The rotor element 3 preferably comprises an LC bandpass filter formed by a series of receive coils RRC1-RRCi, a balanced drive coil RDC and at least one capacitor. The LC bandpass filter center frequency is substantially equal to the frequency of the multi-phase high frequency excitation signal provided in the first conductive pattern of the stator element. After method step S230, method step S240 is performed.

In method step S240, the received signal SR corresponding to the intermediate signal is received at the stator element. More specifically, the intermediate signal SI transmitted from the balanced drive coil RDC of the rotor element 3 is obtained, and the stator element 4 is balanced by the balanced receive coil SRC illustrated with reference to Fig. (SR) to be generated in the receiver. The intermediate signal SI provided to the balanced drive coil RDC of the rotor element 3 is propagated by mutual induction into the balanced receive coil SRC of the stator element 4, Signal (SR). After method step S240, method step S250 is performed.

In method step S250, the received signal SR is processed. More specifically, the received signal is received in a signal processor circuit such as the signal processor circuit 6 illustrated with reference to FIG. The signal processor circuit 6 is configured to process the received signal SR to determine a phase difference between the received signal SR and the reference signal SREF, . The reference signal includes a more appropriate one excitation signal E1-E4 of the high frequency excitation signal SE when constructed as a high frequency excitation signal SE or a multi-weathing high frequency excitation signal SE. The signal processor circuit is operable to determine a relative displacement between the rotor element 3 and the stator element 4 based on quadrature modulation of the received signal and on the basis of using the reference signal SREF as a reference, As shown in FIG. This will be described in more detail with reference to FIG. After the method step S250, the method may end or may be repeated from the method step S200.

According to a preferred embodiment, method step S200 includes generating a multi-phase high frequency excitation signal such as a periodic multi-phase high frequency excitation signal having a plurality of phases. The multi-phase excitation signal includes a plurality of high frequency excitation signals E1-E4 each having a phase of a plurality of phases, as illustrated with reference to Fig. According to the present embodiment, method step S210 includes providing a drive coil that forms a periodically repeated phase pattern P1, wherein the periodically repeated phase pattern is repeated n times along the measurement path, Phase high-frequency excitation signal is supplied to the driving coils of the repeating phase pattern, respectively. This will be described in more detail with reference to FIG.

As an example, the multi-phase excitation signal described above generated in step S200 may be generated to include four high frequency excitation signals each having a different phase. In this example, a series of drive coils of the stator element are configured to form a periodically repeated phase pattern comprising four consecutive drive coils, the first drive coils in the first order of the four consecutive drive coils Phase excitation signal of the multi-phase high frequency excitation signal having a phase of 0 DEG, and the second drive coil in the second order of the four consecutive drive coils is provided to excite the excitation signal of the multi- Signal is supplied, i. E., Shifted 90 DEG with respect to the excitation signal supplied to the first drive coil, and the third drive coil in the third order of the four consecutive drive coils is excited by the excitation signal with 180 DEG phase And the fourth drive coil in the fourth order of the four consecutive drive coils is provided to be supplied with an excitation signal having a phase of 270 degrees. This phase pattern is provided to repeat along the measurement path of the stator element, so that the phase pattern is repeated n times to form n repetitions P1-Pn of the phase pattern described above.

As another example, the described multi-phase excitation signal generated in step S200 may be generated to include three high frequency excitation signals each having a phase. In this example, a series of drive coils of the stator element are configured to form a periodically repeated phase pattern comprising three consecutive drive coils, the first drive coil in the first order of three consecutive drive coils Phase high frequency excitation signal having a phase of 0 DEG and the second drive coil in the second order of the three consecutive drive coils is provided to be supplied with an excitation signal having a phase of 120 DEG That is, the excitation signal supplied to the first drive coil, and the third drive coil in the third order of the three consecutive drive coils is provided to supply an excitation signal having a phase of 240 °. This phase pattern is provided to repeat along the measurement path of the stator element, so that the phase pattern is repeated n times to form n repetitions P1-Pn of the phase pattern described above.

Many modifications and variations will be apparent to those skilled in the art without departing from the scope of the invention as defined in the appended claims. The examples are chosen and described best in order to best explain the principles of the invention and its practical application, so that those skilled in the art will be able to understand various embodiments and various modifications as are suited to the specific use.

Claims (32)

A displacement sensor (2) for a power tool (1), wherein the displacement sensor (2)
And a rotor element (3) configured for relative movement along a measurement path, the stator element including a first conductive pattern (CT1), the rotor element comprising a second conductive pattern (CT2) Wherein the first conductive pattern and the second conductive pattern are mutually inductively coupled and wherein the first conductive pattern is configured to receive the excitation signal SE and the second conductive pattern comprises a first conductive pattern and a second conductive pattern, (SI) in a second conductive pattern caused by mutual induction between the patterns, the intermediate signal representing a relative displacement between the stator element and the rotor element,
Wherein the excitation signal is a high frequency excitation signal (SE) having a constant amplitude. The displacement sensor according to claim 1, wherein the excitation signal is a signal having a frequency selected from a frequency range of 100 KHz to 100 MHz. The displacement sensor according to claim 1, wherein the excitation signal is a signal having a frequency selected from a frequency range of 1 MHz to 10 MHz. 4. The method according to any one of claims 1 to 3, wherein the excitation signal SE is composed of a multi-phase excitation signal comprising a plurality of high frequency excitation signals (E1-E4), each excitation signal having a plurality of phases And a displacement sensor. 5. The displacement sensor of claim 4, wherein the multi-phase excitation signal is a four-phase excitation signal having four phases including a zero degree phase, a 90 degree phase, a 180 degree phase, and a 270 degree phase. 5. The displacement sensor of claim 4, wherein the multi-phase excitation signal is a three-phase excitation signal having three phases including a zero degree phase, a 120 degree phase, and a 240 degree phase. 7. A stator according to any one of the claims 4 to 6, characterized in that the first conductive pattern of the stator element comprises a series of drive coils (SDC1-SDCk) extending along the measuring path of the stator element and a series of drive coils -SDCk) is arranged in a periodically repeated phase pattern (PI) repeated n times along the measurement path, and the phase of the multi-phase signal is supplied to each drive coil of a periodic repeated phase pattern Displacement sensor. 8. A method as claimed in claim 7, characterized in that the phase of the gradually increasing multi-phase excitation signal in the sequence of the drive coils of the periodically repeated phase pattern is configured to be provided to each drive coil of the periodically repeated phase pattern Displacement sensor. 9. A method according to any one of the preceding claims, wherein the second conductive pattern of the rotor element comprises a series of balanced receiving coils (RRC1-RRCi) connected in series and extending along the measuring path of the rotor element, Wherein the measuring path of the rotor element faces the measuring path of the stator element. 9. The method of claim 8 wherein each receive coil (RRC1-RRCi) of a series of receive coils (RRC1-RRCi) forms a periodically repeating balanced two-phase pattern repeated i-1 times along the measurement path So that adjacent loops (L1, L2) of each receiving coil of the series of receiving coils are anti-phase. 11. A motor according to any one of the preceding claims, wherein the rotor element further comprises a balanced drive coil (RDC), the balanced drive coil being coupled to the second conductive pattern, Is configured to transmit an intermediate signal to a balanced receive coil (SRC) of the stator element by mutual induction formed between the coils. 12. The method of claim 11 wherein each balanced drive coil (RDC) and balanced receive coil (SRC) comprises two coil sections (RDCA-RDCB, SRCA-SRCB) Wherein the current flow in the coil section is configured to flow in opposite directions to each other along the measurement path of the rotor element and the stator element. 13. A device according to any one of the preceding claims, further comprising a signal generating circuit (6) coupled to a first conductive pattern of the stator element, the signal generating circuit generating an excitation signal, And to provide an excitation signal to the first conductive pattern to apply energy to the pattern. 14. A device according to any one of the preceding claims, further comprising a single-phase signal processor circuit (5), wherein the signal processor circuit is arranged to provide an output signal (SOUT) representative of the relative displacement between the rotor element and the stator element And receive and process a single-phase received signal (SR) corresponding to an intermediate signal (SI) received at the stator element. 15. A method according to claim 14, wherein the signal processor circuit is arranged to detect the phase difference between the single-phase received signal (SR) and the reference signal (SREF) corresponding to the excitation signal (SE) And a phase detection circuit (13) configured to process the single-phase received signal (SR). The phase detector of claim 15, wherein the phase detection circuit comprises: an I / Q (I / Q) configured to output quadrature signals (I1 and Q1) representative of the phase difference between the received signal (SR) and the reference signal Wherein the demodulation circuit is a demodulation circuit. 17. A rotor according to any one of claims 1 to 16, characterized in that the rotor element is configured to be attached to a first moving part of the power tool, and the stator element is configured to be attached to a second stationary part of the power tool Displacement sensor. 18. The displacement sensor according to any one of claims 1 to 17, wherein the rotor element and the stator element are formed as annular discs. 19. A rotor according to any one of the preceding claims, characterized in that the rotor element and the stator element are formed from a printed circuit board (PCB) having conductive traces, each forming a first conductive pattern and a second conductive pattern Displacement sensor. 20. The displacement sensor according to any one of claims 1 to 19, wherein the rotor element comprises at least one capacitance configuration configured to provide noise suppression. 20. A displacement sensor according to any one of the preceding claims, wherein the rotor element comprises at least one capacitance layer forming at least one capacitor to provide noise suppression. A method for sensing a displacement between two relatively moving parts of a power tool (1), the method comprising:
- generating an excitation signal SE,
- providing an excitation signal to the first conductive pattern (CT1) of the stator element (4)
- generating an intermediate signal (SI) within the second conductive pattern (CT2) of the rotor element (3) by mutual induction between the first conductive pattern and the second conductive pattern, Representing the relative displacement between the elements,
Wherein the step of generating an excitation signal comprises generating a high frequency excitation signal having a constant amplitude. 2. The method of claim 1, wherein the step of generating the excitation signal comprises generating a high frequency excitation signal having a constant amplitude. 23. The method of claim 22,
- receiving a single-phase received signal (SR) corresponding to an intermediate signal (SI) in the stator element,
- processing the single-phase received signal to determine the relative displacement between the rotor element and the stator element. ≪ RTI ID = 0.0 > Way. 24. The method of claim 23,
The step of processing the received signal to determine the relative displacement between the rotor element and the stator element comprises the steps of detecting the phase difference between the reference signal SREF corresponding to the excitation signal SE and the received signal SR And processing the single-phase received signal. 2. A method for sensing displacement between two relatively moving parts of a power tool (1). 25. The method according to any one of claims 22 to 24,
- transferring an intermediate signal from a balanced drive coil (RDC) of the rotor element coupled to the second conductive pattern, characterized in that it comprises the steps of: - transferring an intermediate signal from a balanced drive coil Lt; / RTI > 26. The method of claim 25,
- in a balanced receiving coil (SRC) of the stator element coupled inductively to a balanced drive coil (RDC) of the rotor element, a signal corresponding to the intermediate signal (SI), transmitted from the balanced drive coil of the rotor element Further comprising the step of receiving a single phase receive signal (SR). ≪ Desc / Clms Page number 12 > 27. A method as claimed in any one of claims 22 to 26, wherein generating the excitation signal comprises generating a high frequency multi-phase excitation signal having a constant amplitude and a plurality of phases A method for sensing a displacement between two relatively moving parts of a moving object. 28. A method as claimed in claim 27, wherein the multi-phase excitation signal comprises a zero degree phase, a 90 degree phase, a 180 degree phase and a 270 degree phase, the displacement between the two relatively moving parts of the power tool Lt; / RTI > 28. A method as claimed in claim 27, wherein the multi-phase excitation signal comprises a 0 degree phase, a 120 degree phase and a 240 degree phase, for sensing the displacement between two relatively moving parts of the power tool (1) Way. 30. The method according to any one of claims 27 to 29,
- arranging a series of drive coils (SDC1-SDCk) extending along the measurement path of the stator element to form a first conductive pattern of the stator element in a periodically repeated phase pattern (P1) repeated n times along the measurement path , ≪ / RTI &
- supplying a phase of the multi-phase signal to each drive coil of a periodically repeated phase pattern, characterized in that it comprises a step for sensing the displacement between two relatively moving parts of the power tool (1) . 23. The method of claim 22,
- filtering the intermediate signal using an LC bandpass filter to attenuate noise outside the band, characterized in that it comprises the steps of: Way. 32. The method according to any one of claims 22 to 31,
- coupling the stator element to the stationary portion of the power tool,
- coupling the rotor element to the moving part of the power tool,
Characterized in that said moving part is moved with respect to said stationary part. ≪ Desc / Clms Page number 13 >

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